The three-phase inverter power supply usually needs to feed multiple loads simultaneously, which requires high reliability of power supply. When a short-circuit fault occurs in a load branch, the inverter should have the ability to limit the fault current and provide enough current to cooperate with the breakers to disconnect the faulty branch, and then the inverter output voltage needs to rise to the rated voltage quickly to resume normal power supply to other healthy loads. However, the output voltage recovery process after clearing the fault is prone to overvoltage phenomenon. To solve the above problem effectively, this paper analyzes the mechanism of overvoltage in the fault recovery process, then proposes a smooth recovery method by adding the parallel virtual impedance, and analyzes the design and implementation of virtual impedance. Finally, the effectiveness of the proposed method is verified by the experimental results.

virtual impedance,three-phase stand-alone inverter,Load asymmetric short-circuit fault,smooth recovery